Spray slow cooker with cooking spray.
Layer half the sliced potatoes in bottom.
Add half the kielbasa over potatoes.
Sprinkle half the diced onion on top.
Mix sour cream, soup, and melted butter.
Pour half the cream mixture over layers.
Add remaining potatoes, kielbasa, and onion.
Pour remaining cream mixture on top.
Sprinkle garlic, paprika, salt, and pepper.
Cover and cook on low 4-5 hours.
Add shredded cheese in final 30 minutes.
Garnish with fresh chives before serving.